This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. To examine the effects of smoking cessation and smoking resumption on insulin resistance and its markers, cardiovascular risk factos, changes in body composition and fat distribution, and changes in the metabolism of body fuel substrates in humans.